Field device of automation technology and method for its manufacture

ABSTRACT

An epoxide polymer foam for a field device of automation technology comprising a measuring transducer for ascertaining a measurement signal and a measurement transmitter for output of a measurement signal ascertained, physical variable of a medium in a containment and/or a tube or pipe and/or a measurement signal ascertained property of the material of the medium, wherein the field device has at least one housing of the measuring transducer and/or of the measurement transmitter, in which electronic components of the measuring transducer and/or of the measurement transmitter are arranged, characterized in that the electronic components are embedded in an epoxide polymer foam, which is a reaction product of a self foaming, potting compound comprising at least the following components: 25 to 75 wt-% of a diglycidyl ether resin; at least one amine containing hardening system comprising a Mannich base; and at least one foaming agent, and a method for manufacturing a field device of automation technology.

The invention relates to a field device of automation technology asdefined in the preamble of claim 1 and to a method for its manufacture.

Potting compounds are applied for various reasons in a field device. DE10 2007 058 608 A1 discloses a field device having an embedding mass,which contains spherical, gas-filled, hollow bodies. These serve forEx-m protection.

Field devices can because of their broad utility be applied insituations where they are subject to especially high temperaturefluctuations. This leads to material expansions and contractions withinthe housing, which can cause defective measurements or in the extremecase can lead to the failure of electronic components.

Starting from this state of the art, an object of the present inventionis to provide a field device and a method for its manufacture, whichfield device is usable in a greater temperature range and has a lowerfailure rate in the case of temperature change loading.

The invention achieves this object by a field device as defined in claim1 and by a method as defined in claim 11.

A field device of the invention of automation technology includes ameasuring transducer for ascertaining a measurement signal and ameasurement transmitter for output of a measurement signal ascertained,physical variable of a medium in a containment and/or a tube or pipeand/or a measurement signal ascertained property of the material of themedium.

A measuring transducer can, for example, in the case of amagneto-inductive flow measuring device be composed of a magnet systemand measuring electrodes arranged on a measuring tube. The measurementsignal 3 is a voltage tapped on the measuring electrodes.

The measurement transmitter can, based on this tapped voltage, ascertaina flow, e.g. a flow rate or a total flow over a given period of time, ora flow velocity of the medium through the measuring tube. The selectedone of these is then the physical variable 5. In the case of other fielddevices, the physical variable 5 can be, for example, the fill level ofthe medium in the container or the pressure of the medium or thetemperature of the medium.

The property of the material of the medium 5 can be e.g. the thermalconductivity, electrical conductivity, viscosity, pH or, in given cases,the concentrations of individual components in the medium.

The field device includes at least one housing of the measuringtransducer and/or of the measurement transmitter. I.e. the housing canbe for the measuring transducer, the measurement transmitter or both.Thus, there are e.g. compact temperature measuring devices ormagneto-inductive flow measuring devices, in the case of which both themeasurement transmitter as well as also the measuring transducer arecontained in one housing. More frequently, however, measurementtransmitter and measuring transducer are spaced from one another. Thus,the separation can be e.g. by way of a neck on the sensor.

Arranged in the aforementioned housings can be electronic components,which are for the measuring transducer and/or the measurementtransmitter.

Such electronic components can be, for example, boards and componentsarranged thereon, planar coils, conventional coils, resistors,especially measuring resistors, cable and the like.

The above-described kinds of field devices, for example, in the field offlow measuring technology, are known per se. Typically, such fielddevices are calibrated as a function of temperature and applied inpractice under quite different temperature conditions.

For reduction of temperature related, material stresses, electroniccomponents are according to the invention embedded in an epoxide polymerfoam, which is a reaction product of a self foaming, potting compound,especially a flowable, self foaming, potting compound, comprising atleast the following components:

-   a) 25 to 75 wt-% of a diglycidyl ether resin;-   b) at least one amine containing hardening system comprising a    Mannich base; and-   c) at least one foaming agent.

The self foaming, potting compound can be provided e.g. just shortlybefore its application against and around the electronic components.Self foaming means that the potting compound itself forms a polymerfoam.

An epoxide polymer foam from the aforementioned self foaming, pottingcompound has an especially optimized compressibility. Additionally, alsoundercuts in an installation space of the housing become occupied byfoam. All together, especially advantageously, the entire free volume ofthe housing can be filled with foam. It is, in such case, however,preferable not to provide a purely-surficial application of foam ontothe individual electronic components. Instead, the foam should extendover the entire breadth of the housing. In this way, an especiallyadvantageous and insulating securement of the electronic components isenabled.

Preferably, the polymer foam fills at least 50 vol-% of the housing andespecially preferably the entire housing.

Through use of the aforementioned, special, epoxide polymer foam forembedding electronic components, temperature related material stressesare advantageously reduced in the case of temperatures, such as occur infield devices in automation technology. Additionally, the epoxidepolymer foam has a high foam stability, so that the electroniccomponents do not shift. Additionally, the force of the foam on theelectronic components is small, so that they are not damaged due totemperature related stresses.

Advantageous embodiments of the invention are subject matter of thedependent claims.

Any epoxide polymer foam, which is manufacturable from theaforementioned components, can be applied in the context of the presentinvention.

However, the components of the potting compound are most often notcompletely consumed during the foaming. Therefore, the components of thepotting compound are also detectable in the epoxide polymer foam. Eachof the components a)-c) can advantageously be present in the resultingepoxide polymer foam with a residual content of greater than at least100 ppm, preferably with a residual content of at least 500 ppm.

The diglycidyl ether resin can advantageously be a bisphenol-A- and/orbisphenol-F diglycidyl ether resin.

The foaming agent can advantageously be a polymethyl hydrosiloxane,which preferably is contained in the potting compound up to 5 wt-%. Thisfoaming agent can in combination with an amine and/or an alcohol releaseCO2. The amine or alcohol can be provided, for example, by the hardener.

Advantageously, the Mannich-base is a reaction product ofpara-formaldehyde with 4-tert-butylphenol and/or a reaction product of4,4′-isopropylidenediphenol with 1,3-phenylmethanamine, which preferablyis contained at up to 15 wt-% in the potting compound. These tworeaction products enable an optimal gel time for allowing foaming tooccur. They enable an optimal pore size of preferably 0.1 to 0.5 mm(image analysis) in the foam and/or a defined consistency of the foam ata preferred Shore hardness of D 65-75 (per ISO 868).

The potting compound can additionally advantageously contain as anadditional component

-   d) a reactive thinner, wherein the reactive thinner comprises    preferably at least one aliphatic diglycylether with the general    structural formula:

-   -   wherein R=butyl- or hexyl-. In this way, the viscosity and the        flowability of the foam can be optimally set.

The potting compound can advantageously additionally comprise as anadditional component

-   e) a flame retarding and/or foam stabilizing filler.

This can be e.g. an aluminum oxide and/or an aluminum hydroxide as aflame retarding component, while use of silicon oxide and/or calciumcarbonate rather effects foam stabilizing properties.

The potting compound can additionally advantageously have as anadditional component

-   f) a dispersion additive for stabilizing the filler in the potting    compound.

The potting compound, especially the hardening system, canadvantageously contains one or more of the following additionalcomponents:

-   g1) one or more fatty acids, preferably with a chain length of    greater than C18, especially preferably unsaturated fatty acids with    a chain length of greater than C18, especially in the form of dimers    and/or oligomers;-   g2) one or more reaction products with tall oil fatty acids and    polyamines, preferably with TETA and/or TEPA;-   g3) one or more polymers formed from a reaction of    4,4′-isopropylidenediphenol and/or 4,4′-methylene bisphenol with a    reaction product of 1-chlorine-2,3-epoxypropane and    3-aminomethyl-3,5,5-trimethylcyclohexane and/or with a reaction    product of 1-chlorine-2,3-epoxypropane and    trimethylhexane-1,6-diamine;-   g4) a trimethylhexane-1,6-diamine,    3-aminomethyl-3,5,5-trimethylcyclohexane and/or    1,3-phenylmethanamine;-   g5) an aromatic alcohol, preferably 4,4′-isopropylidenediphenol,    benzyl alcohol, salicylic acid, 4-tert-butylphenol and/or phenol;    and/or-   g6) a liquid won from cashew nut shells.

The filler can advantageously have two different granulations with afirst grain size of 0.3 to 2.5 μm and a second grain size of 15 to 25 μm(determined by Mastersize 3000 of Malvern), wherein the ratio of thefiller with the first grain size to the filler with the second grainsize lies between 1 to 3 and 2 to 3. The filler with the larger grainsize supplementally stabilizes the foam, while the filler with smallergrain size prevents the filler with the larger grain size from settlingout.

A method for manufacturing a field device of automation technology asclaimed in one of the preceding claims includes steps as follows:

-   a) arranging electronic components and, in given cases, further    components of the field device within a housing of a measuring    transducer and/or measurement transmitter

The additional components can, in such case, be non-electroniccomponents, e.g. mechanical components.

-   b) introducing the self foaming, potting compound, especially the    flowable, self foaming, potting compound, into the electronics    housing to form an epoxide polymer foam; and-   c) closing, especially medium tightly closing, the housing following    a reaction time for foaming and curing, i.e. hardening, the epoxide    polymer foam and providing the operation ready field device.

This providing can include, for example, also the loading of softwareinto the field device and a programming.

The subject matter of the invention will now be explained in greaterdetail and by means of a concrete example of an embodiment.

In automation technology, especially in process automation technology,field devices are often applied, which serve for registering and/orinfluencing process variables. Serving for registering process variablesare sensors, which, for example, are integrated in fill-level measuringdevices, flow measuring devices, pressure- and temperature measuringdevices, pH-redox potential measuring devices, conductivity measuringdevices, etc., which register the corresponding process variables, filllevel, flow, pressure, temperature, pH-value, and conductivity. Servingfor influencing process variables are actuators, such as, for example,valves or pumps, via which the flow of a liquid in a pipe or tubesection, and the fill level in a container, can be changed. Referred toas field devices are, in principle, all devices, which are applied nearto the process and which deliver, or process, process relevantinformation. In connection with the invention, the terminology, fielddevices, thus refers also to remote I/Os, radio adapters, and,generally, electronic components 8, 9, which are arranged at the fieldlevel. A large number of such field devices are produced and sold by thefirm, Endress+Hauser.

A field device is, in such case, especially selected from a groupcomposed of flow measuring devices, fill-level measuring devices,pressure measuring devices, temperature measuring devices, limit levelmeasuring devices and/or analytical measuring devices.

Flow measuring devices include especially Coriolis-, ultrasonic-,vortex-, thermal- and/or magneto inductive flow measuring devices.

Fill level measuring devices include especially microwave fill levelmeasuring devices, ultrasonic, fill level measuring devices, timedomain, reflectometric, fill level measuring devices (TDR), radiometricfill level measuring devices, capacitive fill level measuring devices,inductive fill level measuring devices and/or temperature sensitive filllevel measuring devices.

Pressure measuring devices include especially absolute-, relative- anddifference pressure measuring devices.

Temperature measuring devices include especially measuring devices withthermocouples and temperature dependent resistances.

Limit level measuring device include especially ultrasonic, limit levelmeasuring devices and/or capacitive, limit level measuring devices.

Analytical measuring devices include especially pH sensors, conductivitysensors, oxygen- and active oxygen sensors, (spectro)-photometricsensors, and/or ion-selective electrodes.

Typically, one distinguishes in the case of the aforementioned fielddevices between a measuring transducer unit 2 and a measurementtransmitter unit 4. These two units 2, 4 can be spaced from one anotherand connected together by a so-called sensor neck. This serves, amongother things, for thermal decoupling of the measurement transmitter 4from the measuring point. Known, however, are also field devices, inwhich the measuring transducer unit 2 and the measurement transmitterunit 4 are united in one housing for compact construction.

Both the measuring transducer unit 2 as well as also the measurementtransmitter unit 4 will, in general, contain electronic components 8, 9.Typical electronic components of the measuring transducer unit 8 can beassociated with sensor elements and can be, for example, coils of amagnet system, a measuring resistor for ascertaining the temperature ofthe medium, ultrasonic transducers of a bimorph drive and/or the like.Electronic components of the measurement transmitter unit 9 can be e.g.measurement amplifier components, data storage area units, CPU-, orcomputer, units and/or the like.

The electronic components 8, 9 are arranged in a measuring transducer-and/or measurement transmitter housing 6, 7 and are embedded in a foammass in this housing 6, 7.

In the case of securing electronic components 8, 9 in the housing 6, 7of a field device by means of an epoxide polymer foam 1, certainprerequisites must be taken into consideration.

A feature of the epoxide polymer foam 1 is definitely itscompressibility. This is required, in order to accommodate temperaturechange related, material stresses, in order to protect the sensitiveelectronic components 8, 9. Such material stresses could lead, amongother things, to defective measurements and in the extreme case to afailure of the electronic component 8, 9.

Field devices are, in such case, exposed to a temperature change due tothe most often absolutely necessary calibration. A field device ofprocess automation can additionally be applied in all kinds of differentenvironmental conditions. Thus, the field device can, for example, beutilized both for flow measurement of cryogenic liquids as well as alsoheated oil mixtures or vapors.

Ideally, the epoxide polymer foam 1 should also provide a thermalinsulation of the electronic components 8, 9 from the housing wall ofthe housing 6, 7 of the field device surrounding the electroniccomponents 8, 9.

The starting composition for manufacture of the epoxide polymer foam 1will now be explained in greater detail. The epoxide polymer foam 1 isformed from a self foaming, potting compound.

The self foaming, potting compound is based on a diglycidyl ether resin,preferably a bisphenol-A- and/or bisphenol-F diglycidyl ether resin.This base resin is preferably contained in the educt mixture at a levelbetween 25 to 75 wt-%. It can, thus, preferably be a one component baseresin, which is made to react.

The preferred average molecular weight of the diglycidyl ether resinamounts to greater than 500 g/mol, preferably greater than 700 g/mol.

The preferred viscosity of the diglycidyl ether resin, per DIN 53019,amounts to 8 to 13 Pa*s at 25° C.

The self foaming, potting compound additionally includes a foamingagent. The foaming agent is preferably polymethyl hydrosiloxane. Thefoaming agent, especially polymethyl hydrosiloxane, can preferably becontained at up to 5 wt-% in the potting compound. In a preferredembodiment of the invention, polymethyl hydrosiloxane is contained inthe potting compound at between 0.3 and 2 wt-%.

Polymethyl hydrosiloxane is, normally, utilized as a water repellingagent. In the present case, however, a side reaction of this agent isutilized. It reacts with an amine and/or with an alcohol to give offCO2. The amine can be, for example, an amine contained in the pottingcompound. Advantageously, polymethyl hydrosiloxane provides an optimalCO2 release velocity.

A further component of the potting compound is a hardening systemcomprising at least one amine and/or an alcohol. This hardening systemcomprises additionally a Mannich base. The amine and/or the alcohol canpreferably be introduced in a preliminary reaction with the diglycidylether resin and additional optional ingredients. Then, the Mannich baseis added, so that gel formation occurs. It has surprisingly been foundthat, by adding the Mannich base, the hardening time can be optimallyset in such a manner that gel formation begins during the development ofthe foaming agent and the epoxide mass hardens shortly after thefoaming.

Thus, the complete curing of the potting compound to the epoxide polymerfoam 1 can occur in a preferred time span of, for instance, 0.4 to 2hours, especially within 0.5-1 hour. On the whole, use of theMannich-base in the amine- and/or alcohol containing hardening systemgives the potting compound sufficient time for foaming.

The potting compound, in such case, does not collapse, nor does it growtoo rapidly and it has the right viscosity, such that undercuts withinan electronics housing 6, 7 are filled with the polymer foam, such beingnot the case for many foam systems, such as structural foam.

Through use of the aforementioned hardening system, thus, a controlledand unhurried rising of the polymer foam from the potting compound canoccur, without the system collapsing. The self foaming, potting compoundcan be introduced at room temperature.

As components of the hardening system, the self foaming, pottingcompound includes preferably at least one or more of thehereinafter-described components.

One or more fatty acids can be applied in the hardening system.Preferred fatty acids have a chain length of greater than C18. The fattyacids are preferably unsaturated fatty acids. Preferably, the fattyacids are dimers and/or oligomers. Alternatively or supplementally tothe fatty acids, the hardening system can also contain one or morereaction products with tall oil fatty acids and polyamines, especiallyTETA and/or TEPA. The concentration of the one or more fatty acids or ofthe aforementioned reaction product and/or the reaction products in thepotting compound is preferably up to 15 wt. %.

Alternatively or supplementally, the hardening system in the selffoaming, potting compound can contain a polymer, which is formed from4,4′-isopropylidenediphenol and/or 4,4′-methylene bisphenol reacted with1-chlorine-2,3-epoxypropane reacted with3-aminomethyl-3,5,5-trimethylcyclohexane and/ortrimethylhexane-1,6-diamine. This polymer can be present in the pottingcompound at up to 15 wt-%.

Another alternative or additional component of the hardening system canbe trimethylhexane-1,6-diamine and/or3-aminomethyl-3,5,5-trimethylcyclohexane and/or 1,3-phenylmethanamine atup to 15 wt-%.

An alternative or optional component of the hardening system can be areaction product of para-formaldehyde with 4-tert-butylphenol and/or areaction product of 4,4′-isopropylidenediphenol with1,3-phenylmethanamine. This component can likewise be present at up to15 wt-% in the potting compound.

Furthermore, an alternative or optional component of the hardeningsystem can be at least one aromatic alcohol at up to 15 wt-%. Thisaromatic alcohol can preferably be selected from the following group:4,4′-isopropylidenediphenol, benzyl alcohol, salicylic acid,4-tert.-butylphenol and/or phenol.

Furthermore, alternatively or optionally, the potting compound can haveup to 10 wt-% of a liquid won from cashew nut shells.

Besides the base resin, the hardening system and the foaming agent, theself foaming, potting compound can have yet other components, whichsupplementally improve the properties of the epoxide polymer foam 1.

Thus, the potting compound can optionally have one or more reactivethinners. This reactive thinner lessens the viscosity of the pottingcompound, in order to enable a better flow of the potting compound inthe housing 6, 7 and a better embedding and wetting of the electroniccomponents 8, 9 and the housing wall. A reactive thinner is, in suchcase, not to be confused with a thinning means, since the reactivethinner requires most often significantly lower amounts, in order toreduce the viscosity of the potting compound to a desired targetviscosity. As reactive thinner for the self foaming, potting compound inthe context of the present invention, preferably an aliphaticdiglycylether or a plurality of aliphatic diglycylethers with thegeneral structural formula:

can be applied, wherein R=butyl or hexyl.

The self foaming, potting compound can optionally contain fillers. Thefillers serve primarily for providing a flame retarding effect and/or anadditional stabilizing of the foam and can preferably be contained inthe potting compound at up to 70 wt-%, especially preferably from 50 to70 wt-%. These fillers comprise one or more of the following compounds:silicon dioxide, calcium carbonate, aluminum hydroxide and/or aluminumoxide.

In a preferred embodiment, the potting compound contains filler in atleast two different grain sizes. A first grain size has according tomeasurement by laser diffraction a D₁₀ of 0.5 μm, a D₅₀ of 1 μm and aD₉₀ of 2.4 μm. Fillers with this first grain size are contained in apreferred embodiment at at least up to 10 wt-% in the potting compound.

A second grain size has according to measurement by laser diffraction aD₁₀ of 3 μm, a D₅₀ of 20 μm and a D₉₀ of 50 μm. Fill substances withthis second grain size are contained in a preferred embodiment at atleast up to 30 wt-% in the potting compound.

The ratio of filler with the first grain size to filler with the secondgrain size is from 1 to 3 to 2 to 3 in the potting compound

The application of fillers with at least two grain sizes supplementallyincreases the stability of the polymer foam and lessens sedimentation ofthe filler with the greater grain size.

Furthermore, optionally present in the self foaming, potting compoundcan be a dispersion additive, which controls flocculation of fillers inthe potting compound. Such dispersion additives avoid especially thesettling and loss of fillers from the potting compound. Preferreddispersion additives include one or more polycarboxylic acid polymers.In such case, preferably the concentration of dispersion additive is 5wt-% or less.

In the following, a concrete example of an embodiment will be given,which in the context of the present invention is introduced as selffoaming, potting compound into a housing of a measuring transducer 2and/or measurement transmitter 4 and hardens to an epoxide polymer foam1 while embedding electronics components located in the housing 6, 7.

Thus, the following is an example of a particular potting compound:

Potting Compound 1 (130 parts total) Epikote Resin 169 40 HeloxyModifier BD 5 BYK-P 105 2 Bluesil WR 68 1 Apyral 2E 60 Aradur HY 842 10D.E.H. 615 5 adduct of Epikote Resin 169 (40 parts by 7 weight) withVestamin TMD (100 parts by weight)

In such case, Epikote Resin 169 is a diglycidylether base resin;

Heloxy Modifier BD an aliphatic diglycidylether as a reactive thinner,BYK-P 105 a polycarboxylic acid polymer as dispersion additive, BluesilWR 68 a polymethyl hydrosiloxane as foaming agent,Apyral 2E a flame retarding filler in the form of aluminum hydroxide,Aradur HY 842 a polyamidoamine hardening means as part of a hardeningsystem,D.E.H. 615 a Mannich base as part of the hardening system, anda reaction product of Epikote Resin 169 (40 weight %) with Vestamin TMD(100 weight %) as part of the hardening system.

The latter is reacted before addition to the potting compound, wherein apart of the added excess—of Vestamin TMD reacts with the base resin. Alarge part of Vestamin does not react with the base resin and is presentin the epoxide polymer foam 1 in detectable amounts after the reactionforming the epoxide polymer foam 1, just as in the case of the Mannichbase.

The self foaming, potting compound is prepared only very shortly,preferably less than 5 minutes, for example, 3 minutes, before pouringonto the electronic components 8, 9. The self foaming, potting compoundis prepared by mixing the foaming agent and/or the individual hardenercomponents into the diglycidyl ether resin. Gel formation occursconcurrently with foaming and a housing 6, 7 filled out with epoxidepolymer foam 1 can result in a time span of, for example, 40 minutes. Inthe case of application of polymethyl hydrosiloxane as foaming agent,the foam formation can advantageously occur at normal environmentaltemperatures between 20 and 40° C.

In a preferred embodiment, the potting compound contains bisphenol, butis, however, free of additional phenols and/or phenol derivatives.

1-11. (canceled)
 12. An epoxide polymer foam for a field device ofautomation technology, comprising: a measuring transducer forascertaining a measurement signal and a measurement transmitter foroutput of a measurement signal ascertained, physical variable of amedium in a containment and/or a tube or pipe and/or a measurementsignal ascertained property of the material of the medium, wherein thefield device further comprises at least one housing of the measuringtransducer and/or of the measurement transmitter, in which electroniccomponents of the measuring transducer and/or of the measurementtransmitter are arranged, wherein the electronic components are embeddedin the epoxide polymer foam, which is a reaction product of a selffoaming, potting compound, comprising at least the following components:a) 25 to 75 wt-% of a diglycidyl ether resin; b) at least one aminecontaining hardening system comprising a Mannich base; and c) at leastone foaming agent.
 13. The epoxide polymer foam as claimed in claim 12,wherein: each of the components a)-c) is contained in the epoxidepolymer foam with a residual content of greater than at least 100 ppm,preferably with a residual content of at least 500 ppm.
 14. The epoxidepolymer foam as claimed in claim 12, wherein: the diglycidyl ether resinis a bisphenol-A- and/or bisphenol-F diglycidyl ether resin.
 15. Theepoxide polymer foam as claimed in claim 12, wherein: the foaming agentis a polymethyl hydrosiloxane, which is preferably contained in thepotting compound at up to 15 wt-%.
 16. The epoxide polymer foam asclaimed in claim 12, wherein: the Mannich base is a reaction product ofpara-formaldehyde with 4-tert-butylphenol and/or a reaction product of4,4′-isopropylidenediphenol with 1,3-phenylmethanamine, which ispreferably contained in the potting compound at up to 15 wt-%.
 17. Theepoxide polymer foam as claimed in claim 12, wherein: the pottingcompound additionally contains as an additional component d) a reactivethinner, wherein the reactive thinner comprises preferably at least onealiphatic diglycylether with the general structural formula:

wherein R=butyl- or hexyl-.
 18. The epoxide polymer foam as claimed inclaim 12, wherein: the potting compound additionally comprises as anadditional component e) a flame retarding and/or foam stabilizingfiller, which preferably is an aluminum oxide, an aluminum hydroxide, asilicon oxide and/or a calcium carbonate.
 19. The epoxide polymer foamas claimed in claim 18, wherein: the potting compound additionallycomprises as an additional component f) a dispersion additive forstabilizing the filler in the potting compound.
 20. The epoxide polymerfoam as claimed in claim 12, wherein: the potting compound, especiallythe hardening system, contains one or more of the following additionalcomponents: g1) one or more fatty acids, preferably with a chain lengthof greater than C18, especially preferably unsaturated fatty acids witha chain length of greater than C18, especially in the form of dimersand/or oligomers; g2) one or more reaction products with tall oil fattyacids and polyamines, preferably with TETA and/or TEPA; g3) one or morepolymers formed from a reaction of 4,4′-isopropylidenediphenol and/or4,4′-methylene bisphenol with a reaction product of1-chlorine-2,3-epoxypropane and 3-aminomethyl-3,5,5-trimethylcyclohexaneand/or with a reaction product of 1-chlorine-2,3-epoxypropane andtrimethylhexane-1,6-diamine; g4) a trimethylhexane-1,6-diamine;3-aminomethyl-3,5,5-trimethylcyclohexane and/or 1,3-phenylmethanamine;g5) an aromatic alcohol, preferably 4,4′-isopropylidenediphenol, benzylalcohol, salicylic acid, 4-tert.-butylphenol and/or phenol; and/or g6) aliquid won from cashew nut shells.
 21. The epoxide polymer foam in claim12, wherein the filler has two different granulations with a first grainsize of 0.3 to 2.5 μm and a second grain size of 15 to 25 μm, whereinthe ratio of filler with the first grain size to filler with the secondgrain size lies between 1 to 3 and 2 to
 3. 22. A method formanufacturing a field device of automation technology, comprising thesteps as follows: a) arranging electronic components and, in givencases, further components of the field device within a housing of ameasuring transducer and/or measurement transmitter; b) introducing theflowable, self foaming, potting compound into the electronics housing toform an epoxide polymer foam; and c) closing, especially medium tightlyclosing, the housing following a reaction time for foaming and d)curing, i.e. hardening, the epoxide polymer foam and providing theoperation ready field device.